A typical application for the cleanable heated valve is in process industries that require a supply of high purity water within prescribed contamination limits supplied in custom designed systems with specific materials, finishes, process conditions and cleaning requirements, where cleaning can range from simple common cleaning methods to sanitisation and or sterilisation.
Quite often high purity water is required for specific operations in a number of industries, and is required to be supplied at various flow rates through smooth easy to clean valves. Whilst there are commercially available techniques to maintain water quality within the closed piping system, maintaining unfavourable conditions for microbiological activity in the downstream side of the valve and valve outlet that is exposed to the environment, can be a problem especially in systems below 60° C.
The moist, cold to warm environment of the discharge side of the valve and valve outlet, which is exposed to the room air, provides an ideal atmosphere for microbiological activity. Depending upon the size of the outlet and the temperature of the water it is possible for a plug of water to hold-up in the nozzle when not in use further aggravating the problem.
It is possible to steam sterilise the downstream side of the valve and outlet prior to use but this requires more valves, a pure steam supply and associated hardware. It is also not practical to steam sterilise a valve outlet where the water is frequently required. Steam can also be a safety hazard and for the abovementioned reasons steam is not a good general solution to the problem. It is also possible to sanitise the outlet by a number of methods including hot water, chemicals and oxidising agents. Like steam, these methods introduce complications and can only be effective during the sterilisation/sanitisation cycle once removed or when the outlet is reused contamination can begin to reoccur.
Another typical application for the cleanable heated valve is in process industries where there is a need to supply, isolate or regulate the flow of fluids that exhibit enhanced properties at elevated temperatures, in smooth cleanable valves.
A typical example could be the transfer of food products that are processed in systems of specific materials, finishes and clean-ability requirements. Another example could be the transfer of a product that is a liquid above a specific temperature but solidifies below that specific temperature or liquids that tend to create cleaning difficulties at certain temperatures and require cleanable systems including valves.
Another typical application for the cleanable heated valve is isolation valves at the boundary of systems or heat treatment apparatus containing items, products, medium, waste or the like being heat treated, sterilised or decontaminated. It is usually necessary to demonstrate that the required treatment temperature is achieved in all exposed internal regions of the said system or heat treatment apparatus. Quite often these said systems or heat treatment apparatus contain valves to serve a multitude of purposes. Said valves can often provide “cold spots” in such applications due to the mass of metal exposed to the colder outer environment making it difficult to achieve the required treatment temperatures.
In the abovementioned applications it is typical to externally wrap the piping and/or valves and the like with electrical heated wire coils or small bore steam piping, known as heat tracing, or to use steam jackets. Whilst these techniques are successful on interconnecting pipes it is difficult to provide enough energy from the outer exposed surfaces to heat-up the thick mass of metal found in smooth cleanable type valves to achieve the required temperatures on the inside surfaces of the valve. Heat tracing and associated protection coverings when applied to valve bodies can be bulky, difficult to apply efficiently and difficult reapply after removal for maintenance and can create external cleaning issues in hygienic industries.
There are patents existing for heated valves in the casting molten metal industry, refer U.S. Pat. Nos. 5,752,562, 5,531,245
The valves covered in the above mentioned patents comprise of internal joints, crevices, sliding grooves and attachments. The resulting nooks and crannies provide areas for product to lodge, harbouring microbiological contamination and creating difficulties for cleaning. This makes the said valves unsuitable for hygienic industries or where cleaning or sterilisation is an issue. The design of these said valves for the molten metal industry could also contain “cold spots” due to changes in material and limited contact with the metallic body of the heating element. Also, given that the heating element is in contact with the process fluids, there are potential issues with localised hot spots that can denature proteins and certain food products, gaps where product and wastes can lodge between the heater and valve body. It would also be difficult for the said valves to comply with the material compatibility, surface finish, certification and traceability requirements of the food and health science industries.